The duct should vent to the outside.
Install a roof vent for exhagust fan.
Install exhaust fan on flat roof by saum hadi posted on february 17 2020 dia keepa vent an aluminum roof attic ventilation flat roof exhaust vent hood range cap roof roof vents for proper attic ventilation exhaust vent hood range cap roof.
The lower half of the flange sits on top of the shingles.
Apply a bead of asphalt roof cement on the bottom of the vent.
Nail the lower corners with roofing nails and tar the heads.
Then use a screw to secure the duct connector to the edge of the hole so that it will line up with the exhaust on the fan housing.
Slide the vent under the shingles so they cover the top half of the vent flange.
From inside the attic drive a nail through the roof directly above the bathroom vent fan.
Exhaust fans mounted on an exterior wall vent directly outside without any ductwork required.
Center the nail between two rafters.
Ceiling mounted fans typically use ducts hidden in the walls ceiling or attic to reach a safe exit point on the roof or a wall.
From the roof find the nail and use the utility knife to cut roof shingles from around the nail.
Installing an exhaust fan requires electrical connections and ventilation to the exterior of your home.